In detective stories, as the plot thickens, an unexpected clue often delivers more questions than answers. In this case, the scene is a mountain on Mars. The clue: the chemical compound silica. Lots of silica. The sleuths: a savvy band of Earthbound researchers whose agent on Mars is NASA's laser-flashing, one-armed mobile laboratory, Curiosity.

The Curiosity rover has found much higher concentrations of silica at some sites it has investigated in the past seven months than anywhere...

This self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Big Sky" site, where its drill collected the mission's fifth taste of Mount Sharp.

The scene combines dozens of images taken during the 1,126th Martian day, or sol, of Curiosity's work on Mars (Oct. 6, 2015, PDT), by the Mars Hand Lens Imager (MAHLI) camera at the end of the rover's robotic arm. The rock drilled at this site is sandstone in the Stimson geological unit inside Gale Crater. The location is...

A new study from the team behind NASA's Mars Science Laboratory/Curiosity has confirmed that Mars was once, billions of years ago, capable of storing water in lakes over an extended period of time.

Using data from the Curiosity rover, the team has determined that, long ago, water helped deposit sediment into Gale Crater, where the rover landed more than three years ago. The sediment deposited as layers that formed the foundation for Mount Sharp, the mountain found in the middle of...